Whole-mount in situ hybridization of Pitx2 (A, C, E) and Bmp6 (B, D, F) expression in the ventral pharyngeal tooth plate (VTP) (A, B), dorsal pharyngeal tooth plate (DTP) (C, D), and in the oral jaw (E, F) in 15 day post fertilization freshwater larvae. Pitx2 expression is detected in the inner and outer dental epithelium and not in dental mesenchyme. Bmp6 is detected in the inner (but not outer) dental epithelium and condensing dental mesenchyme in early tooth germs. After calcification begins, Bmp6 expression is only detected in dental mesenchyme (see panel D). Expression of both genes is detected in similar patterns in developing oral and pharyngeal tooth germs. Inner dental epithelium = black arrowheads (black caret on late stage), outer dental epithelium = white arrowheads (white caret on late stage), dental mesenchyme = black caret. Also see Fig. S1. Scale bar = 50 μm.